IPA: /ˈkoʊziər/
KK: /ˈkoʊziər/
More comfortable and warm in a way that makes you feel relaxed and at home.
The new blankets made the living room feel cosier during the winter months.
Cosier is derived from "cozy" (from the Scottish word "cosy", meaning comfortable or snug) and the suffix "-er" (meaning more). The word "cosier" means more comfortable or snug than something else.
Think of the Scottish word for comfortable, 'cosy', and remember that 'cosier' means more comfortable.